A loader is a construction machine typically used to transport a load of material, such as aggregate construction or mining material, from one place, such as a pile of stored material, to another, such as a truck used for hauling the material to another location. For example, a loader may be used to load a dump truck full of material or to transport material from a pile to a specific place where it is used, such as trench. Typically, loaders are wheeled or tracked vehicles having a large bucket on one end and include hydraulics or other mechanisms for raising and lowering the bucket and tilting the bucket. However, a loader can also be a stationary machine that is immobile, but used to transport a load from one place to another, for example from a pile to the bed of a nearby dump truck. Generally, a loader is any device capable of using a bucket or other appropriate support structure to transport a payload from one place to another place.
Often, it is desirable to know the weight of a payload. For example, dump trucks used on the highway typically must abide by laws restricting how much weight they can carry and the restrictions are typically determined by a government highway authority. Depending on the density of the material loaded into a truck, it is possible to load more than the maximum allowed amount into the bed of the truck. In addition, loading too much weight into a truck can also cause premature wear to the truck's suspension, drive train, and other parts affected by weight. In other instances, it may be desirable to know the weight of the payload. For example, when material is sold according to weight, knowing an amount of material loaded into a truck can provide a basis to calculate a cost of the loaded material.
To determine the weight of a payload, loaders often include bucket scales. A bucket scale is a system integrated into the loader which measures the weight of a payload. Typically, bucket scales measure hydraulic pressures associated with the bucket, such as pressures present in hydraulic cylinders used for lifting the bucket up and down and for tilting the bucket about a pivot point. One problem with bucket scales is that the pressures in the relevant portions of the hydraulic system depend on the center of gravity (CG) of the payload. In particular, a payload concentrated in one location of a loader bucket may cause pressure values to be different than if the same payload is concentrated in another portion of the bucket. For instance, the same payload concentrated towards the front of a bucket will cause pressures in the relevant hydraulics to be different than if the payload is concentrated towards the back of the bucket. Consequently, as the same payload can cause varying measurements in bucket scales depending on the distribution of the payload, bucket scales can give inaccurate measurements of payload weight unless the distribution of the payload is taken into account.